Temperature responses of the Rubisco maximum carboxylase activity across domains of life: phylogenetic signals, trade-offs, and importance for carbon gain

[eng] Temperature response of ribulose-1,5-bisphos- phate carboxylase/oxygenase (Rubisco) catalytic properties directly determines the CO2 assimilation capacity of photosynthetic organisms as well as their survival in environments with different thermal conditions. Despite unquestionable importance of Rubisco, the comprehensive analysis summarizing temperature responses of Rubisco traits across lineages of carbon-fixing organisms is lacking. Here, we present a review of the temperature responses of Rubisco carboxylase specific activity (kc ) within and cat across domains of life. In particular, we consider the var- iability of temperature responses, and their ecological, physiological, and evolutionary controls. We observed over two-fold differences in the energy of activation (DHa) among different groups of photosynthetic organisms, and found significant differences between C3 plants from cool habitats, C3 plants from warm habitats and C4 plants. According to phylogenetically independent contrast ana- lysis, DHa was not related to the species optimum growth temperature (Tgrowth), but was positively correlated with Rubisco specificity factor (Sc/o) across all organisms. However, when only land plants were analyzed, DHa was positively correlated with both Tgrowth and Sc/o, indicating different trends for these traits in plants versus unicellular aquatic organisms, such as algae and bacteria. The opti- mum temperature (T ) for kc correlated with S for land opt cat c/o plants and for all organisms pooled, but the effect of Tgrowth on Topt was driven by species phylogeny. The overall phylogenetic signal was significant for all analyzed parameters, stressing the importance of considering the evolutionary framework and accounting for shared ancestry when deciphering relationships between Rubisco kinetic parameters. We argue that these findings have important implications for improving global photosynthesis models